Adjustable ammunition booster sprockets



y 1956 c. B. PEARSON 2,756,636

ADJUSTABLE AMMUNITION BOOSTER SPROCKETS File 11y 18, 1950 INVENTOR. \02 I08 CHARLEEBFEARSUN.

0 BY Z0 & E 8 6b ATTORNEY 'tion.

United States Patent i ADJUSTABLE AION BOOSTER SPROCKETS Application July 18, 1950, Serial No. 174,419

2 Claims. CI. 89-33) This invention relates to improvements in booster units of the type used for feeding ammunition to automatic guns.

It is an established practice to assemble ammunition into belt formation so that each consecutive round of such ammunition is made available to be loaded automatically into a gun as rapidly as the gun can be fired. The actual mechanical operation of moving the belt is performed by the gun during the cycle which includes firing, extraction, and reloading.

1 It is also an established practice to provide an auxiliary means which provides, if necessary, all the force needed for moving the belt when such force is too large to be supplied by the ammunition-feeding mechanism of the gun. Such an auxiliary means is commonly referred to as an ammunition booster for automatic guns, and is comprised of a motor and suitable gearing assembled in a hollow cylindrical member or hub. On the outer surface of the hub, flanges are formed with teeth on their periphery shaped to engage the ammunition in much the same manner as a sprocket wheel engages the rollers of a roller chain.

When the toothed flanges are made integral with the hub or permanently attached thereto, a reversal of the axial position of the ammunition, or a change in the size of ammunition requires a major operation to relocate or replace the flanges, or an entirely different booster unit 1 is required to match the dimensional changes in the ammunition, although all other characteristics of the booster satisfy in every respect the remaining requirements for proper boosting or feeding of different types of ammuni- Itis apparent that such a situation involves considerable expense in time and money to relocate the flanges or to provide the many different booster units required to meet the various conditions, and prevents standardization of parts which is so vital in equipment of this type.

It is therefore the primary object of this invention to provide an ammunition booster unit with a sprocket wheel assembly which can be easily altered to meet a wide Variety of operating requirements, and which can be adapted for use with different types of ammunition, ammunition belts and different types of guns.

It is an additional object of the invention to provide a shock-absorbing ammunition booster with a sprocket wheel assembly having reversible and interchangeable sprocket members.

It is a further object of the invention to provide a booster unit hub having a uniformly cylindrical outer surface on which a pair of sprocket members can be located in different axial positions.

. It is another object to provide such a booster unit in which the sprocket members may be reversely mounted on the hub to effect the change in their axial positions.

It is another object of the invention to provide a selfdriven ammunition booster unit in which the sprocket members can be easily removed, reversed and/0r replaced, without the use of special tools or equipment, to

meet varied operating requirements. It is also an object to provide such a booster unit with a sprocket Wheel having a hub and a pair of ammunition engaging elements which are so constructed as to permit rearrangement of these elements with respect to each other and with respect to the hub without affecting the ability of the elements to simultaneously engage each round in a belt of ammunition.

Other objects and advantages of this invention will become apparent from the following description and the drawing, in which:

Fig. 1 is a side view of a booster unit partly in section and partly in elevation showing a spring shock absorber and a sprocket wheel assembly with a pair of removable sprocket members mounted on a cylindrical hub;

Fig. 2 is an end view of Fig. 1 taken on line 2-2, showing the profile of the sprockets, and the engagement of the sprockets with ammunition in belt or chain formation; the shock absorber is omitted;

Fig. 3 is a fragmentary side view of a sprocket hub and cross-sectional view of the sprocket members comprising a modification of the invention;

Fig. 4 is an end view of the sprocket hub illustrated in Fig. 3 and an end view of the sprocket members;

Fig. 5 is a fragmentary view of a sprocket hub and associated sprocket members of another modification;

Fig. 6 is an end view of Fig. 5;

Fig. 7 is a side view of a sprocket member having an adjustable profile;

Fig. 8 is a view taken on line 8-43 of Fig. 7 showing the sprocket member adjustably positioned on the hub;

Fig. 9 is a side view of the sprocket member showin a different position of profile adjustment;

Fig. 10 is a side view of Fig. 9, with the sprocket members positioned on a hub;

Fig. 11 is a cross-sectional side view of two sprocket members on a hub, showing modifications for profile adjustment.

Referring to Fig. 1, a self-driven booster unit is shown in which a hollow cylindrical hub 12 with a uniformly cylindrical outer surface, is journaled in a frame having a left frame side member 13, and a right frame side member 14. The actual bearings for the hub are formed by the stationary stud 15 having an enlarged cylindrical surface 15-A and by the normally stationary housing of motor 17, .the outer cylindrical surfaces of which form a sliding fit with the inner surface of hub 12. Fitted to one end of the motor housing is a flanged cup 18, the outer end of which extends into a hole in the frame member 14. The screws 20 passing through plate 21 and cup 18 secure said cup to the end of the motor.

The torsion spring 22, which encircles the cup 18, has a lug 23 formed on one end to engage the notch 24 in the flange of cup 18. Formed on the other end of spring 22 is a second lug 25 that engages a hole 26 in the frame member 14.

Motor 17 rotates hub 12 by means of pinion 27, idler gears 28, and an internal gear 29. The stator of the motor 17, which constitutes the housing of the motor, is fastened to frame side-member 14 through and is held normally stationary by coil spring 22. Spring 22 resists the reaction forces exerted on thestator when hub 12 is driven by the rotor and the gears, and transmits these forces, as reaction torque, to the frame member 14 by means of cup 18, notch 24, lug 23, lug 25, and hole 26 in the said frame member 14. This arrangement interposes a shock absorbing means between any load moved by the rotary action of hub 12 and the motor 17. The screws 20, which are threaded into holes 30 of the motor housing, pass through clearance holes in cup 18 and plate 21, and serve to locate the position of arm 31 with respect to the axis of the motor, because the arm 31 is formed as an integral part of the plate 21.

Movement of the arm 31 in a counterclockwise direction, when viewed from the right end, will store energy in the spring in direct proportion to the amount of such movement. Therefore the position of pin 32, which prevents the clockwise movement of arm 31, determines the exact amount of initial force which must be overcome to move arm 31 away from pin 32, and such initial force, expressed in terms of counter torque, can, by the movement of arm 31, be used to actuate suitable indicator mechanisms when desired.

In conventional construction of booster units for feeding ammunition to automatic guns, the sprocket members are formed as an integral part of the hub, or they are attached to the hub in a manner such as to make their removal impossible without special tools and equip ment. The adaptability of booster units so constructed is limited to onetype of ammunition pointed in a single crosswise direction with respect to the belt, which necessitates the use of as many different booster units as there are Calibers of ammunition, and even the ammunition having the same caliber may call for two types of boosters, known as left-hand and right-hand boosters, in order to feed this same ammunition into the left-hand or right-hand gun. The disclosed sprocket wheel assemblies are constructed so as to effect a driving relationship between a hub and a pair of sprocket members maintained in axially spaced positions on the hub by means transversely associated with the hub and abuttingly associated with axial extremities of the sprocket members, as illustrated, such that the hub and sprocket members can be easily disassembled and rearranged to meet different operating requirements without the need of special equipment.

Referring again to Fig. 1, sprocket members and 41, shown in profile in Fig. 2, are slidably keyed to the cylindrical outer surface of hub 12 by shoulder keys 42 and 43 welded or otherwise fixed to the hub, and are positioned in spaced relationship with respect to each other, as shown in Fig. l, by the abutment of the key shoulders against axial extremities of the sprocket members adjacent hub 12, and by the abutting relationship between other axial extremities of the sprocket members adjacent said hub and retaining rings 44 and 45 Which removably engage annular ring seats provided in the hub. Sprocket members 40 and 41, constructed to slide freely and interchangeably on the end portions of the hub, are provided with similar axially-extending keyway portions 46 and 47 having axially extending keyways which drivingly engage keys 42 and 43 to form driving connections between the sprocket members and hub 12.

As shown in Figs. 1 and 2, the toothed portions of sprocket members 40 and 41 are shaped to respectively engage different diametral portions of rounds of ammunition such as round 33, pointed to the left. Kit is desired to drive a belt of ammunition having rounds pointing in the opposite direction, as indicated by round 34, then, after removing the booster unit from the frame, the sprockets are exchanged end for end with respect to the hub; in other words, sprocket member 40 is replaced with sprocket member 1 and member 41 is replaced with member 40.

Keyway portions 46 and 47, have a length greater than the thickness of the toothed portions of the sprocket members to permit the construction of different sprocket members with toothed portions in relatively difierent positions along the keyway portions, whereby hub 12 is universally adapted to accommodate ammunition belts comprised of rounds having a different length and/or a difierent set of sprocket-engagement areas without altering the axial positions of the shoulder key-s and the retaining rings. In the modifications shown in Figs. 3 and 4, the sprocket members 50 and 52 are mounted on hub 51 which can be driven in the same manner as hub 12 of Fig. 1. As indicated in the figures, the sprocket members are slidably keyed to the hub so that their axial position on the hub may be adjusted, but they are prevented frorn rotating around the hub by a key 53. The key 53 is shown extending the full length of the hub 51, and is rigidly attached thereto so as to provide a driving connection between the hub and the sprocket members. An integral portion 54 of key 53 securely holds the threaded rod 55 which passes through the sprocket members 50 and 52. By adjusting the nuts 56 and 57, the sprocket member 52 can be made to occupy ditferent positions on the hub 51, and by similar adjustment of nuts 58 and 59, the member 50 can be made to occupy any desired axial position on hub 51.

Although Figs. 3 and 4 show only one key and one adjusting means, it is understood that more may be added if necessary.

In Figs. 5 and 6, sprocket members 60 and 62 are slidably mounted on a hub 64, and engage a key attached to said hub so that a driving connection exists between the hub and the the sprocket members. Keys or keepers 61 and 63 are shaped so as to transversely straddle key 65 and fit into notches 66 and 67 to hold the members 60 and 62 in the desired axial positions. Screws 68 and 69 hold the keepers in their respective positions. The number of notches and their spacing determines the extent and nature of adjustment. It is understood that hub 64 can be driven in a manner similar to that illustrated in Fig. 1.

A composite, or multiple sprocket member having an adjustable contour adaptable for use in driving ammunition belts is illustrated in Figs. 7, 8, 9, and 10. The member 70 is composed of three sections, all of them having the same toothed profile. In Figs. 7 and 8, the sections 71, 72, and 73 are shown in alignment so that the spaces between the teeth can engage rounds of ammunition having cylindrical shapes as indicated by the dotted circles 74.

While the completely composite member 70 is slidably mounted on a hub 80, its rotation on the hub is prevented by inwardly projecting lugs 75 forming keys on the bore of section 72, which lugs engage keyways 82. The serrations 77 formed on both sides of section 72 and on the inner sides of sections '71 and 73 are for preventing rotation with respect to each other when clamped together by the machine screw and nut 78. For the sake of clarity, the serrations are shown in only one tooth of member 70, which is formed by sections 71, 72, and 73. However, it is understood that the serrations 77 can be formed over all or any part of the coacting surfaces of sections 71, 72, and 73.

Annular grooves 84 in the outer surface of hub are spaced to provide various axial locations for the member 70 which is held in position by retaining rings 86.

Adjustment of the contour of toothed member 70 is provided by the relative positions of sections 71 and 73 with respect to section 72, as shown in Figs. 9 and 10, wherein section 71 has been moved clockwise from the keyed section 72, and section 73 has been moved counterclockwise from the keyed section 72. Fig. 9 clearly shows the changed contours of the composite sprocket member 70 so as to fit rounds of ammunition having cylindrical shapes as indicated by the dotted circles 76. The serrations 77, shown in Fig. 8, have been omitted from the sections 71, 72, and 73 in Fig. 10 to indicate that such serrations, or equivalent means to prevent slippage between the sections, may or may not be used.

There are several practical modifications of the sprocket member 70, two of which are shown in Fig. 11. The sections 101 and 103 are keyed to the hub to prevent their rotation with respect thereto. Sections 102 and 104, and sections 106 and 108 have suitable toothed profiles to provide adjustment similar to that shown in Figs. 9 and 10.

The three-section construction of the adjustable sprocket member 70, shown in Figs. 7 through 11, is to provide an adjustment which will preserve the pitch between the teeth on a constant pitch circle so that, when two or more of such members 70 are positioned on a hub, the axis of each round of ammunition engaged by the said members will be parallel in all respects to the axis of the hub.

By the use of adjustable sprocket members 70 on a self-driven hub, which has provision for different axial locations of the members 70, the adjustments of the booster sprocket can be made to fit ammunition of several different calibers, and may be made to operate as a righthand or left-hand sprocket member.

Although a limited number of embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that other forms and combinations can be made without departure from the spirit of the invention.

What is claimed as new is:

1. In a booster unit for moving rounds of ammunition arranged in belt formation, a sprocket wheel assembly characterized by adaptability to drivingly engage various ammunition belts, said sprocket wheel assembly comprising: a hub having a central axis and a cylindrical outer surface of uniform diameter; first means fixedly associated with the cylindrical outer surface of the hub in parallel relationship with respect to the axis thereof such as to condition said hub as a driving element; a pair of interchangeable sprocket members reversibly mounted in respective axial positions on the cylindrical outer surface of the hub, each sprocket member including an axially extending first portion slidably engaged with the first means such as to effect a driving connection with the hub, and a radially extending second portion adapted to drivingly engage the ammunition belt, said first and second portions being so constructed that the axial extremities of the first portion defines a length thereof exceeding the thickness of the second portion, and so arranged with respect to each other that a reversal in the axial mounting of each sprocket member in its respective axial position on the hub effects a change in the axial position of the belt-engaging second portion of said each member with respect to the cylindrical outer surface of the hub; and second means transversely associated with the first means and the hub, and abuttingly associated with the axial extremities of the first portions of the sprocket members such as to maintain said sprocket members in their respective axial positions on said cylindrical hub surface.

2. In a booster unit for moving rounds of ammunition arranged in belt formation, a sprocket wheel assembly characterized by adaptability to drivingly engage various ammunition belts, said sprocket wheel assembly comprising: a hub having a central axis and a cylindrical outer surface of uniform diameter; shoulder keys rigidly fixed to the cylindrical outer surface of the hub in parallel relationship with respect to the axis thereof such as to condition said hub as a driving element; a pair of interchangeable sprocket members reversibly mounted in respective axial positions on the outer cylindrical surface of the hub, each sprocket member including an axially extending keyway portion having an axially extending keyway slidably engaged with one of said keys to effect a driving connection with the hub, and a radially extending toothed portion adapted to drivingly engage the ammunition belt, said keyway and toothed portions being so constructed that the axial extremities of the keyway portion defines a length thereof exceeding the thickness of the toothed portion, and so arranged with respect to each other that a reversal in the axial mounting of each sprocket member in its respective axial position on the hub effects a change in the axial position of the belt engaging toothed portion of said each member with respect to the cylindrical outer surface of the hub; and means fixedly associated with the keys and the hub transversely of the hub axis for maintaining the sprocket members in their respective axial positions on said hub, said means including the shoulders formed on the keys and removable retaining rings disposed in annular ring seats formed in the outer hub surface, said shoulders and retaining rings being in abutment with the axial extremities of the keyway portions ,of said sprocket members.

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